1. Field of the Invention
This invention relates to an ATM multiplex apparatus transmitting audio and various types of data by using an ATM technology, and a congestion reporting method used in the apparatus.
2. Description of Related Art
An ATM multiplex apparatus of prior art is disposed between an ATM network and various types of terminals such as frame relay (FR) terminals and data terminals, and comprises an interface unit interfacing with the terminals, a multiplex unit multiplexing data to be sent from the terminals, a main control unit controlling actions of the interface unit and the multiplex unit.
In the ATM multiplex apparatus of prior art, a congestion level of data storing medium in the multiplex unit is monitored by the main control unit, and various congestion control processing is executed in accordance with a monitoring result.
For example, when the frame relay terminal is connected to the ATM multiplex apparatus, the congestion control is performed by having the main control unit obtains information regarding a detection of the congestion at the multiplex unit, and then the main control unit reports the congestion at the multiplex unit to an interface unit of the frame relay terminal.
Prior art of the congestion control technology is disclosed in, for example, Japanese Patent Application Laid-Open 07-015436, 07-147592, 09-083566, and 9-284338.
The congestion reporting method used in the congestion control technology of prior art is realized by a software processing to transmit the congestion control report to the interface unit of the frame relay terminal via the main control unit. Accordingly, a real time congestion control is not possible due to a time lag between the detection of the congestion and the reporting to the interface control unit.
An object of the present invention is to provide a congestion reporting method enabling a faster congestion control of a frame relay terminal, and an ATM multiplex apparatus such a congestion reporting method.
The object of the present invention is accomplished by providing units for transmitting and receiving exclusive signals to report a congestion in between a multiplex unit and a frame relay interface control unit in an ATM multiplex apparatus. Accordingly, a congestion control may be executed in real time since it becomes possible to report a congestion level of a data storage medium of the multiplex unit directly to the frame relay interface control unit using the exclusive congestion reporting signals.
The object of the present invention is also accomplished by providing an ATM multiplex apparatus connected to information terminals for multiplexing information to be communicated and transmitting the multiplexed information via an ATM network, comprising an interface unit interfacing with the information terminals, a multiplex unit multiplexing information from the information terminals, a congestion level detect unit detecting a congestion level of the multiplex unit, and a congestion signal report unit generating signals indicative of a congestion level detected by the congestion level detect unit and outputting the signals to the interface unit, wherein the interface unit accepts the signals indicative of the congestion level, and executes a congestion control for the information terminal in accordance with the congestion level indicated by the signals.
The object of the present invention is also accomplished by providing a congestion reporting method for an ATM multiplex apparatus multiplexing and transmitting information, including the steps of generating signals indicative of a congestion level of a data storage medium of a multiplex unit disposed in the ATM multiplex unit for executing a congestion control of a frame relay interface, and outputting the generated signals in real time to an interface unit interfacing with a frame relay terminal.